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A clinical trial was conducted to assess the feasibility, safety, and efficacy of the atrial septal defect (ASD) occlusion system for transcatheter closure of secundum ASD and patent foramen ovale (PFO) after episodes of cerebral embolism. Occlusion was attempted in 200 patients aged 1 to 74 years (mean 32). The procedure failed in 26 patients (13%); the device was retrieved through a catheter in 20 and through surgery in 6 patients. Procedure-related complications necessitating surgical removal of the device included device embolization in 2, device entrapment within the Chiari network in 1, frame fracture in 1, and perforation of atrial wall in 2. All 6 patients experienced an uneventful postoperative course. An additional 11 patients (6%) underwent surgical removal of the device during follow-up. There were 163 patients (81%) with an implanted ASD occlusion system at follow-up of from 6 to 36 months (mean 17). Thrombus formation around the device was detected by transesophageal echocardiography in 9 patients 1 to 4 weeks after implantation. One of these patients (who had a coagulation factor XII deficiency) suffered a cerebral thromboembolism. Late atrial wall perforation (5, 6, and 8 months after implantation) occurred in 3 adult patients. Infectious endocarditis developed in 2 adult patients (1%). No late device embolization and no atrioventricular valve injury occurred. An asymptomatic device frame fracture was found in 14% and frame deformity in 4% of all patients during the follow-up period of >230 patient-years. Immediately after closure, a moderate/large residual shunt remained in 8% and a small shunt in 29% of patients. After 1 year, a moderate/large shunt was present in 2% and a small one in 26% of patients. During a total follow-up of 49 patient-years, only 1 of 46 patients with PFO had a transient neurologic event after the closure. The study indicates that patients with centrally situated secundum ASD and those with PFO after cerebral embolism can be treated with this system with a high success rate and an acceptable morbidity. [ABSTRACT FROM AUTHOR]

Nitric oxide-induced vasodilator capacity greatly varies among children with pulmonary hypertension and elevated vascular resistance. The decline of this selective response seems to parallel the progression of established vascular disease and thus may be helpful for the selection of patients for operation.

Ventricular tachycardia (VT) and sudden death are rare but recognized complications after surgical repair of tetralogy of Fallot. We prospectively studied 31 patients (19 boys and 12 girls, mean age +/- standard deviation 7 +/- 4 years) with postoperative tetralogy of Fallot, by means of right-sided cardiac catheterization, 24-hour Holter monitoring, body-surface and intracavitary signal-averaging (gain 10(5) to 10(6), filters of 100 and 300 Hz) and programmed ventricular stimulation (1 and 2 extrastimuli, 3 basic cycle lengths, right ventricular apex and outflow tract). All patients were asymptomatic and none had documented or suspected ventricular arrhythmias. Ventricular late potentials were detected in 10 of 31 patients (32%) and spontaneous ventricular arrhythmias in 12 of 31 patients (39%). No sustained VT was induced by programmed ventricular stimulation but nonsustained VT was induced in 3 patients (10%). Patients with inducible VT more often had late potentials (3 of 3 vs 7 of 28, p less than 0.01), and spontaneous ventricular premature complexes (VPCs) during Holter monitoring (3 of 3 vs 9 of 28, p less than 0.05). To predict VT inducibility, late potentials had a sensitivity of 100%, a specificity of 75%, a positive predictive value of 30% and a negative predictive value of 100%. For spontaneous VPCs, the figures were 100, 68, 25 and 100%, respectively. It is concluded that shortly after repair of tetralogy of Fallot, the presence of both spontaneous VPCs and ventricular late potentials are associated with an increased incidence of inducible VT. Conversely, the absence of VPCs and ventricular late potentials may identify patients at low risk of subsequent ventricular arrhythmias.

Arrhythmias are common in the natural history as well as in the late postoperative course of patients with atrial septal defect (ASD); electrophysiologic disturbances may result from the ASD itself or from surgery. Electrophysiologic studies were performed in 18 children (mean age 10 years) both before and after surgical closure of the ASD. Sinus node (SN) function, conduction intervals and refractory periods (atrial and atrioventricular [AV] nodal) were determined. Before surgery, corrected SN recovery time was prolonged in 14 patients; the mean value for the group was 357 +/- 163 ms. The AH interval was slightly prolonged, as were AV nodal refractory periods. Postoperatively, SN recovery time decreased in all patients who remained in sinus rhythm (p less than 0.02), but 5 patients had atrial ectopic rhythm. The AH interval decreased significantly (p less than 0.02), as did the refractory periods, mainly for the AV node (p less than 0.01). The pacing rate at which second-degree AV block occurred increased. Thus, closure of ASD improves AV conduction, decreases AV nodal refractory periods and improves SN function, probably by suppressing rightsided heart volume overload. However, SN function may be lost, probably as a result of the operative procedure.

This study was conducted to assess the incidence of abnormalities of ventricular depolarization in sinus rhythm after repair of tetralogy of Fallot and their relation to spontaneous ventricular arrhythmias. Forty-four patients were studied, 10 before surgery (mean age 6.9 years) and 34 after repair (mean age 8.1 years, mean age at surgery 6.5 years, mean interval between surgery and evaluation 11 months). Evaluation was performed by means of body surface and intracavitary signal-averaging techniques, by recording local right ventricular (RV) electrograms at several sites and by 24-hour Holter monitoring (n = 28). No electrophysiologic abnormality was observed in children before surgery. Ventricular late potentials were detected in 18 patients (53%) after repair. Body surface detection of ventricular late potentials was frequently masked by the postoperative right bundle branch block pattern. Local RV electrograms were fractionated in 11 cases (32%) (mean duration 103 +/- 33 ms), most often in the RV outflow tract (n = 9), but no relation was found between fragmentation of RV electrograms and the presence of ventricular late potentials. Spontaneous ventricular arrhythmias occurred in 12 children after repair (43%), but were complex in only 4 patients (14%). There was no correlation between spontaneous ventricular arrhythmias and the presence of ventricular late potentials, presence of fractionated RV electrograms, presence of a proximal right bundle branch block or postoperative hemodynamic status.(ABSTRACT TRUNCATED AT 250 WORDS)

To assess the effect of verapamil in children with congenital heart disease after surgical correction, an electrophysiologic study was undertaken in 19 patients, 0.8 to 15 years old. Atrial pacing and programmed atrial extrastimulation were performed before and 5 mn after intravenous administration of verapamil. A significant increase in conduction time and refractory periods was observed at the atrioventricular node level. Dual or accessory atrioventricular pathways, present in 14 cases, appear to have been suppressed in 9. The effect on the sinus node was of particular interest: The corrected sinus node recovery time was strongly prolonged by verapamil in 6 patients, 5 of whom had undergone surgery with extensive atrial reconstruction (Senning 2, anomalous pulmonary venous return 3) and 1 of whom had undergone correction of tetralogy of Fallot. Additional effects of verapamil were the disappearance of a sinus node entrance block in 8 patients and emergence of an ectopic pacemaker in 6. Although verapamil has electrophysiologic properties that should make it a useful drug in the treatment of reentry tachycardia, caution is indicated after extensive atrial surgery because sinus node depression may occur.